"Quit Before Age 50 to Halve Lung Cancer Risk"…The Miracle of 15 Years of Smoking Cessation

National Cancer Center 2.97 Million People Aged 30 and Over Followed for 16-17 Years

Quitting smoking before the age of 50 reduces the risk of developing lung cancer by up to 57% compared to those who continue to smoke.

Citizens smoking cigarettes in a downtown smoking booth Photo by Jo Yongjun jun21@

The research team led by Professors Jin-Kyung Oh and Eun-Jung Park from the National Cancer Center Graduate School of International Cancer Studies announced that people who quit smoking for 12 years have nearly half the risk of developing lung cancer compared to those who continue smoking. This study was published in the JAMA Network Open, a sister journal of the American Medical Association.

The research team classified participants based on their smoking status during health checkups in 2002-2003 and tracked changes in smoking status every two years thereafter into the following groups: continuous smokers, relapsers, temporary quitters, complete quitters, and non-smokers. Following these participants until 2019, the study found that those who had completely quit smoking for more than 12 years had a 17% lower overall cancer risk compared to continuous smokers. Specifically, the risk of lung cancer was reduced by 42%, liver cancer by 27%, stomach cancer by 14%, and colorectal cancer by 20%.

The study also confirmed that the timing of smoking cessation affects cancer risk. People who quit smoking after the age of 50 had a reduced cancer risk compared to continuous smokers: 16% lower for all cancers, 40% lower for lung cancer, and 12% lower for liver and stomach cancers. In contrast, those who quit before the age of 50 saw even greater reductions: 19% lower for all cancers, 57% lower for lung cancer, and 18% lower for liver and stomach cancers.

The longer the duration of smoking cessation, the greater the reduction in cancer risk. For those who quit smoking for 15 years, the risk of all cancers was 50% that of continuous smokers. Additionally, the risk of lung cancer was 71%, liver cancer 55%, stomach cancer 50%, and colorectal cancer 52% lower than that of continuous smokers.

Smoking cessation clinic counseling scene at a public health center.
[Photo by Ministry of Health and Welfare]

Professor Jin-Kyung Oh, the lead researcher, stated, “We confirmed that quitting smoking for more than 10 years significantly reduces the risk of cancer, especially being effective in preventing lung cancer. Maintaining consistent smoking cessation is important for cancer prevention.” He added, “Regardless of age, in other words, even if quitting at a later age, smoking cessation greatly reduces the risk of cancer. Particularly for lung cancer, quitting before middle age is more effective for prevention.”

Meanwhile, lung cancer is the leading cause of cancer death worldwide, with approximately 2.2 million new cases and about 1.8 million deaths annually. According to the 2022 major cancer mortality report by the National Cancer Center, 22.4% (83,378 people) of the total 372,939 deaths were due to cancer. Among these, lung cancer accounted for 22.3% (18,584 people), ranking first in cancer deaths in South Korea.

The causes of lung cancer can be divided into environmental and genetic factors. The most representative environmental factor is smoking. It has been proven that cigarettes contain more than 50 carcinogens. Besides direct smoking, passive smoking, radon, occupational exposure to carcinogens such as asbestos, arsenic, and nickel, smoke generated during cooking, air pollution, and fine dust are also known to increase the risk of lung cancer.

This content was produced with the assistance of AI translation services.